Aluminum-containing high corrosion-resistant magnesium alloy and preparation method thereof

Abstract

The application relates to an aluminum-containing high-corrosion-resistant magnesium alloy and a preparation method thereof. The aluminum-containing high-corrosion-resistant magnesium alloy contains, in mass fraction, 6-10wt% of Al, 0.05-1.5wt% of Ce, 0.05-0.5wt% of Mn, and the balance of Mg and inevitable impurities. The aluminum-containing high-corrosion-resistant magnesium alloy has a microstructure composed of a large number of fine point-shaped beta-Mg 17 Al 12 phase net structure, which can effectively block the expansion of corrosion to the deep base as a corrosion barrier. The rare earth element Ce and the Al element added in the application can enter the oxidation film of the magnesium base in the form of CeO2 and Al2O3, and promote the densification of the oxidation film and the corrosion product film on the magnesium base surface. The high-corrosion-resistant magnesium alloy has a corrosion weight loss rate of only 0.058mg / cm 2 / day after being soaked in a 3.5wt% NaCl solution for 6 days, and a corrosion weight loss rate of only 0.0681mg / cm 2 / day after a 5wt% NaCl neutral salt spray test for 3 days, and exhibits excellent corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of magnesium alloys, in particular to a high corrosion-resistant magnesium alloy containing aluminum and a preparation method thereof. BACKGROUND

[0002] As the lightest structural metal material, magnesium alloy has a wide application prospect in the fields of automobile, 3C electronic products, aerospace and biomedical materials due to its low density, high specific strength, excellent thermal conductivity and damping performance, good electromagnetic shielding performance and biocompatibility. However, magnesium is extremely prone to corrosion in the thermodynamic aspect because of its low standard electrode potential (-2.37 V / SHE) and more importantly, magnesium is more prone to corrosion in the kinetic aspect. This is because the oxidation film of magnesium mainly consists of MgO, which has a PBR (Pilling-Bedworth ratio) less than 1 and cannot effectively cover the surface of the magnesium matrix, thus not having good protective properties. At the same time, the corrosion product film of magnesium mainly consists of Mg(OH)2, which has a flaky structure and the characteristics of loose and porous, and cannot effectively block the expansion of corrosion. Therefore, magnesium will be continuously corroded in the corrosion environment. Like aluminum or titanium metal, its standard electrode potential is also very low, and it also has a high corrosion tendency in the thermodynamic aspect. However, because aluminum and titanium surfaces will form a dense oxide film (PBR>1), which can effectively block the invasion of corrosive media, aluminum and titanium have good corrosion resistance.

[0003] The key to the poor corrosion resistance of magnesium metal is that the oxidation film and corrosion product film of magnesium metal do not have good protective properties. At the same time, the microstructure regulation of magnesium alloy is also an important means to improve the corrosion resistance of magnesium alloy. Therefore, there is a continuous need in the art to develop low-cost high corrosion-resistant magnesium alloys containing aluminum. SUMMARY

[0004] The purpose of the present application is to solve the problem of poor corrosion resistance of magnesium alloy at present, and to provide a guidance idea for the development and design of high corrosion-resistant magnesium alloy from the aspects of microstructure regulation and film densification. The present application provides a low-cost and large-scale application of high corrosion-resistant magnesium alloy containing aluminum and a preparation method thereof.

[0005] The purpose of the present application can be achieved by the following technical solutions.

[0006] In a first aspect, the present application provides a high corrosion-resistant magnesium alloy containing aluminum, the composition of the high corrosion-resistant magnesium alloy containing aluminum is: Al 6-10wt%, Ce 0.05-1.5wt%, Mn 0.05-0.5wt%, and the balance is Mg and unavoidable impurities, based on mass percentage.

[0007] The inevitable impurities include: Fe content not more than 0.01wt%, Ni content not more than 0.005wt%, Cu content not more than 0.005wt%, Si content not more than 0.3wt%.

[0008] In the second aspect, the application provides a preparation method of the high corrosion-resistant magnesium alloy containing aluminum as described in the first aspect, comprising the following steps:

[0009] S1: according to the proportion of the magnesium alloy, the amount of pure magnesium, pure aluminum, Mg-Ce intermediate alloy and Mn source is calculated, then the raw materials are prepared, the oxide skin of the raw materials is removed and preheating treatment is carried out, and the Mn source includes Mg-Mn intermediate alloy or anhydrous manganese chloride;

[0010] S2: under the protection of protective gas, the pure magnesium ingot, the pure aluminum ingot, the Mg-Ce intermediate alloy and the Mn source are melted in a crucible to obtain a magnesium alloy melt;

[0011] S3: under the protection of protective gas, the magnesium alloy melt is stirred, refined, placed and heat preserved, and slagging treatment is carried out to obtain a purified magnesium alloy melt;

[0012] S4: under the protection of protective gas, the purified magnesium alloy melt is cast into a preheated metal mold to obtain a magnesium alloy ingot;

[0013] S5: the magnesium alloy ingot is subjected to solid solution treatment, and then is subjected to aging treatment to obtain the high corrosion-resistant magnesium alloy.

[0014] Compared with the prior art, the application has the following advantages:

[0015] (1) In the application, Al and Ce elements with high PBR are added, and the formed Al2O3 and CeO2 can promote the formation of a dense oxide film on the surface of the magnesium alloy. The corrosion product film formed after the corrosion of ordinary commercial magnesium alloy is mainly composed of Mg(OH)2 and MgO, and due to the loose and porous characteristics, it cannot effectively block the expansion of corrosion, so it shows poor corrosion resistance. The oxide film and the corrosion product film of the high corrosion-resistant magnesium alloy of the application contain CeO2 and Al2O3 formed by the oxidation of the rare earth Ce element, and have a more dense protective film than ordinary magnesium alloy, so it shows excellent corrosion resistance. The corrosion weight loss rate of the high corrosion-resistant magnesium alloy of the application after immersion in 3.5wt% NaCl solution for 6 days is only 0.058mg / cm 2 / day, and the corrosion weight loss rate after 3-day neutral salt spray test in 5wt% NaCl is only 0.0681mg / cm 2 / day. The corrosion rate of the high corrosion-resistant magnesium alloy of the application is much lower than that of the existing commercial AZ91D and AZ31B magnesium alloys.

[0016] (2) The high corrosion resistant magnesium alloy of the present application has a microstructure composed of fine second phase 17 Al 12 The second phase forms a network structure. The present application forms a network structure composed of fine second phase by controlling the microstructure of the magnesium alloy. The network structure composed of fine second phase avoids the strong micro-galvanic corrosion effect between the coarse second phase and the magnesium matrix in the AZ91D magnesium alloy, and thus effectively alleviates the serious pitting corrosion of the magnesium matrix. For example, the ordinary commercial AZ91D magnesium alloy has a strong micro-galvanic corrosion effect between the coarse second phase and the magnesium matrix, and thus exhibits serious pitting corrosion behavior. On the other hand, the network structure of the high corrosion resistant magnesium alloy of the present application can be connected to form a network corrosion barrier during the corrosion process, thereby blocking the further expansion of corrosion. 17 Al 12 The second phase has an accelerating effect on the micro-galvanic corrosion of the magnesium matrix. By reducing the size of the second phase, the micro-galvanic corrosion effect between the second phase and the magnesium alloy can be effectively reduced, thereby effectively alleviating the serious pitting corrosion of the magnesium matrix. For example, the ordinary commercial AZ91D magnesium alloy has a strong micro-galvanic corrosion effect between the coarse second phase and the magnesium matrix, and thus exhibits serious pitting corrosion behavior. On the other hand, the network structure of the high corrosion resistant magnesium alloy of the present application can be connected to form a network corrosion barrier during the corrosion process, thereby blocking the further expansion of corrosion.

[0017] (3) The high corrosion resistant magnesium alloy of the present application only adds a small amount of low-cost rare earth element Ce, and exhibits excellent corrosion resistance. Therefore, the high corrosion resistant magnesium alloy of the present application has the advantage of low cost. More importantly, the high corrosion resistant magnesium alloy of the present application is simple to prepare and easy to mass produce, and has good industrial application value. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the SEM microstructure of the high corrosion resistant magnesium alloy in Example 1 of the present application;

[0019] Figure 2 is the cross-sectional SEM image of the corrosion product film layer of the high corrosion resistant magnesium alloy in Example 1 of the present application after immersion in the corrosion medium for 6 days;

[0020] Figure 3 is the cross-sectional SEM image of the corrosion morphology of the AZ91D magnesium alloy in Comparative Example 1 of the present application after immersion in the corrosion medium for 6 days;

[0021] In the Figure 2 , Epoxy refers to epoxy resin, and Mg Matrix refers to magnesium matrix. In the Figure 3 , Epoxy refers to epoxy resin, Mg Matrix refers to magnesium matrix, corrosion pits refer to pitting corrosion pits, and corrosion products refer to corrosion products. DETAILED DESCRIPTION

[0022] Unless otherwise indicated, all parts and percentages expressed herein are based upon weight and all tests and measurements are conducted synchronously with the filing date of this application. To the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a patent, application or public disclosure incorporated by reference, the meaning or definition assigned to that term in this document shall control. If a specific term is defined both in the present application and in a document incorporated by reference, the definition provided in this document shall control.

[0023] Numerical ranges in this disclosure are approximations, and thus the endpoints of ranges are not to be understood as being significantly bound by the recited starting and ending values. Unless otherwise indicated, all numerical ranges are inclusive of the recited endpoints. A numerical range includes all values from and including the lower and to and including the upper value. For example, a range of "1 to 10" is inclusive of the values 1 and 10 along with all the individual values and sub-ranges therebetween, e.g., 1 to 6.5, 4.3 to 7.8, 5.3, etc. In this disclosure, the use of "or" means "and / or" unless clearly indicated otherwise or dictated by context. Only those components which are necessary for an adequate description of the disclosed compositions and methods are specifically recited.

[0024] With respect to chemical compounds, the singular includes all isomeric forms unless specifically described otherwise. Additionally, the use of "a", "an", or "the" to describe a noun also includes the plural of that noun unless specifically stated otherwise.

[0025] The terms "comprising", "including", "containing", and variations thereof, do not exclude the presence of other components, steps or processes, and are used synonymously with the term "comprising". For the avoidance of doubt, the term "consisting essentially of to the compositions of the present application can include any additional additives, adjuvants or compounds unless specifically stated otherwise. In contrast, the term "consisting of shall exclude any component, step or process not specifically recited. The term "or" as used in the present document means any one member of a set or any combination.

[0026] Highly corrosion resistant magnesium alloy

[0027] As mentioned above, because the PBR of MgO is less than 1, it cannot effectively cover the surface of magnesium alloy, and the corrosion product of magnesium, Mg(OH)2, has the characteristic of loose and porous, and cannot effectively block the spread of corrosion, resulting in the magnesium alloy being prone to corrosion. At the same time, a dense oxide film is formed on the surface of aluminum and titanium, making them have good corrosion resistance. Therefore, in a first aspect, the present application provides an aluminum-containing high corrosion-resistant magnesium alloy.

[0028] In an embodiment, the present application provides an aluminum-containing high corrosion-resistant magnesium alloy, which comprises, in terms of mass percentage: Al 6-10 wt%, Ce 0.05-1.5 wt%, Mn 0.05-0.5 wt%, and the balance being Mg and unavoidable impurities.

[0029] The unavoidable impurities include: Fe content not more than 0.01 wt%, Ni content not more than 0.005 wt%, Cu content not more than 0.005 wt%, and Si content not more than 0.3 wt%.

[0030] In a specific embodiment, the aluminum-containing high corrosion-resistant magnesium alloy described herein can comprise, in terms of mass percentage, 6%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7.0%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9%, 8.0%, 8.1%, 8.2%, 8.3%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8%, 8.9%, 9.0%, or a range or sub-range between any two of these values.

[0031] In a specific embodiment, the aluminum-containing high corrosion-resistant magnesium alloy described herein can comprise, in terms of mass percentage, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 1.0%, 1.05%, 1.1%, 1.15%, 1.2%, 1.25%, 1.3%, 1.35%, 1.4%, 1.45%, 1.5%, or a range or sub-range between any two of these values.

[0032] In an embodiment, the aluminum-containing high-corrosion-resistant magnesium alloy described herein can comprise 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, or a range or sub-range between any two of the numerical values, of Mn, on a mass percentage basis.

[0033] In an embodiment, the aluminum-containing high-corrosion-resistant magnesium alloy comprises: Al 6-9wt%, Ce 0.1-1.0wt%, Mn 0.05-0.3wt%. Impurity elements: Fe content is not more than 0.005wt%, Ni content is not more than 0.001wt%, Cu content is not more than 0.001wt%, Si content is not more than 0.1wt%.

[0034] In an embodiment, the aluminum-containing high-corrosion-resistant magnesium alloy comprises: Al 6-9wt%, Ce 0.1-1.0wt%, Mn 0.05-0.3wt%. Impurity elements: Fe content is not more than 0.005wt%, Ni content is not more than 0.001wt%, Cu content is not more than 0.001wt%, Si content is not more than 0.1wt%.

[0035] In an embodiment, the aluminum-containing high-corrosion-resistant magnesium alloy comprises: Al 6-9wt%, Ce 0.1-1.0wt%, Mn 0.05-0.3wt%. Impurity elements: Fe content is not more than 0.005wt%, Ni content is not more than 0.001wt%, Cu content is not more than 0.001wt%, Si content is not more than 0.1wt%.

[0036] The high-corrosion-resistant magnesium alloy of the present application has a dense protective film formed by CeO2 and Al2O3, which are formed by oxidation of the rare earth element Ce and Al, respectively, and thus exhibits excellent corrosion resistance.

[0037] Method for producing highly corrosion resistant magnesium alloy

[0038] In another embodiment, the present application also provides a method for preparing the high-corrosion-resistant magnesium alloy as described above.

[0039] In an embodiment, the method for preparing the aluminum-containing high-corrosion-resistant magnesium alloy as described above comprises the following steps:

[0040] S1: according to the proportion of the magnesium alloy, the amount of pure magnesium, pure aluminum, Mg-Ce intermediate alloy and Mn source is calculated, and then the raw materials are prepared and the oxide skin is removed and preheated, and the Mn source includes Mg-Mn intermediate alloy or anhydrous manganese chloride;

[0041] S2: under the protection of protective gas, melting pure magnesium ingot, pure aluminum ingot, Mg-Ce intermediate alloy and Mn source in a crucible to obtain a magnesium alloy melt;

[0042] S3: under the protection of protective gas, stirring, refining, standing and holding and slagging treatment of the magnesium alloy melt to obtain a purified magnesium alloy melt;

[0043] S4: under the protection of protective gas, casting the purified magnesium alloy melt into a preheated metal mold to obtain a magnesium alloy ingot;

[0044] S5: solid solution treatment and then aging treatment of the magnesium alloy ingot to obtain the high corrosion-resistant magnesium alloy.

[0045] In one specific embodiment, the step S2 comprises:

[0046] S21: under the protection of SF6 and CO2 mixed gas, melting pure magnesium ingot at 680℃, then adding one of Mn source, Mg-Mn intermediate alloy or anhydrous manganese chloride powder at 720-750℃ and holding for 10-20 minutes;

[0047] S22: under the protection of SF6 and CO2 gas, removing slag on the surface of the melt, adding pure aluminum ingot at 750℃ and holding for 10-20 minutes;

[0048] S23: under the protection of SF6 and CO2 gas, removing slag on the surface of the melt, adding Mg-Ce intermediate alloy at 750℃ and stirring for 3-5 minutes; then holding at 750℃ for 20-30 minutes to obtain the magnesium alloy melt.

[0049] In one embodiment of the second aspect, in S3, the refining temperature is 740-750℃, and the vigorous stirring is performed for 3-5 minutes; the standing and holding temperature is 740-750℃, and the standing and holding time is 40-50 minutes.

[0050] In one specific embodiment, in step S4, the casting temperature is 690-720℃. In one specific embodiment, in step S5, the solid solution temperature is 390-440℃, and the solid solution time is 5-24 hours. In one specific embodiment, in step S5, the aging temperature is 180-250℃, and the aging time is 6-48 hours.

[0051] The application will be further described in detail with reference to the accompanying drawings and specific embodiments, but the protection scope of the application is not limited to the described content.

[0052] Examples 1-8

[0053] The eight embodiments of the high corrosion-resistant magnesium alloy containing aluminum according to the present application, the magnesium alloy of the embodiments 1-8 contains the components shown in Table 1:

[0054] Table 1 Composition of the magnesium alloy of the embodiments 1-7

[0055]

[0056] In the preparation method of the magnesium alloy of the embodiments 1-8, the process parameters of each step are selected as shown in Table 2:

[0057] Table 2 Process parameters of the preparation method of the magnesium alloy of the embodiments 1-8

[0058]

[0059]

[0060] Corrosion performance test of the magnesium alloy according to the present application

[0061] In this embodiment, the magnesium alloy prepared by the above embodiments 1-8 and the magnesium alloy of the comparative examples 1-2 are used as the test objects, and the magnesium alloy of the comparative examples 1-2 is as follows:

[0062] The commercial AZ91D magnesium alloy of the comparative example 1 is directly purchased from the market, and contains the following components with the weight percentage: Al 9.2wt%, Zn 0.44wt%, Mn 0.25wt%, Fe 0.052wt%, Ni 0.0007wt%, Cu 0.0009wt%, Si 0.016wt%.

[0063] The commercial AZ31B magnesium alloy of the comparative example 2 is directly purchased from the market, and contains the following components with the weight percentage: Al 3.12wt%, Zn 0.86wt%, Mn 0.20wt%, Fe 0.089wt%, Ni 0.0002wt%, Cu 0.0005wt%, Si 0.063wt%.

[0064] The corrosion performance test method of the magnesium alloy of the embodiments 1-8 and the comparative examples 1-2 is as follows:

[0065] The magnesium alloy of each group with size of 20x20x5mm was placed in neutral 3.5wt% NaCl solution (solution volume is 600mL) at room temperature 25℃, and the test time is 6 days. The immersion corrosion test is in accordance with national standard GB 10124-88, and the weight loss rate is calculated by the weight difference between the sample before corrosion test and the sample after corrosion test cleaning. The weight loss rate is obtained by dividing the weight difference by the sample surface area and dividing by the test days. The hydrogen gas volume is equivalent to the magnesium corrosion by recording the decrease of the solution in the burette. The hydrogen evolution rate is obtained by dividing the hydrogen gas volume by the sample surface area and dividing by the test days. The corrosion cleaning agent is 200g / L CrO3+10g / L AgNO3, which is the general magnesium alloy corrosion product cleaning method. The weight loss rate and hydrogen evolution rate of each group of magnesium alloy are shown in Table 3.

[0066] Table 3 Corrosion performance test results of magnesium alloy of examples and comparative examples

[0067] Group Weight loss rate (mg / cm 2 / day) Hydrogen evolution rate (mL / cm 2 / day) Example 1 0.058 0.049 Example 2 0.063 0.051 Example 3 0.075 0.068 Example 4 0.065 0.057 Example 5 0.085 0.076 Example 6 0.078 0.070 Example 7 0.085 0.074 Example 8 0.096 0.089 Comparative Example 1 0.27 0.18 Comparative Example 2 0.35 0.24

[0068] As can be seen from Table 1, the weight loss rate of the high corrosion-resistant magnesium alloy of the present application after immersion in 3.5wt% NaCl solution for 6 days is only 0.058mg / cm 2 / day, and the hydrogen evolution rate is only 0.049mL / cm 2 / day. The weight loss and hydrogen evolution rates of the high corrosion-resistant magnesium alloy of the present application are much lower than the corrosion rates of the currently commercial AZ91D magnesium alloy and AZ31B magnesium alloy. The present application realizes the design and preparation of high corrosion-resistant magnesium alloy by means of rare earth Ce micro-alloying and subsequent heat treatment organization regulation process, which weakens the micro-galvanic corrosion between the magnesium matrix and the second phase and forms a corrosion barrier, and promotes the densification of the protective film on the magnesium matrix surface, from two aspects.

[0069] As can be seen from Examples 1-4, when the Al content in the alloy is too low and too high, the corrosion resistance of the magnesium alloy will decrease. This is because when the Al content in the matrix is too low, the magnesium matrix cannot precipitate a large amount of fine β-Mg 17 Al 12 second phase during aging precipitation, so that the corrosion barrier cannot be formed, resulting in the decrease of the corrosion resistance of the matrix. When the Al content is too high, a large amount of Mg 17 Al 12 second phase structure will be formed in the magnesium matrix, which will cause the magnesium matrix to become brittle and the mechanical properties to decrease; on the other hand, a large amount of Mg 17 Al 12 second phase will cause incomplete solid solution to the magnesium matrix during solid solution, which will aggravate the micro-galvanic corrosion between the magnesium matrix and Mg 17 Al 12Micro-galvanic corrosion effect between the second phase and the magnesium matrix. As can be seen from Examples 5-6, too low or too high Ce content will also result in the decrease of the corrosion resistance of the magnesium matrix. When the Ce content in the matrix is too low, the compactness of the corrosion product film formed on the surface of the magnesium matrix will decrease, thus resulting in the decrease of the corrosion resistance of the magnesium matrix. When the Ce content in the matrix is too high, a large number of Al4Ce second phases with high potential will be formed, which will accelerate the strong micro-galvanic corrosion effect between the Al4Ce phase and the magnesium matrix, thus resulting in the decrease of the corrosion resistance of the alloy. As can also be noted from Examples 7-8, too low or too high Mn content will also result in the decrease of the corrosion resistance of the alloy. On the one hand, when the Mn content is too low, the Fe-removing effect of the Mn element will become poor, the allowable limit of Fe element in the magnesium matrix will decrease, and the influence of the impurity Fe element on the corrosion resistance of the magnesium matrix will be intensified. On the other hand, when the Mn content is too high, a large number of Al-Mn-Ce phases with ultra-high potential will be formed in the magnesium matrix, which will further intensify the micro-galvanic corrosion between the second phase and the magnesium matrix, thus resulting in the decrease of the corrosion resistance of the alloy.

[0070] Figure 1 SEM microstructure of the high corrosion-resistant magnesium alloy in Example 1. As can be seen, the high corrosion-resistant magnesium alloy of the present application has a microstructure composed of fine point-like precipitated β-Mg 17 Al 12 The network structure composed of the second phase. The network structure composed of the fine precipitated second phase is connected together, and the corrosion barrier formed thereby can effectively block the further invasion of corrosion. Meanwhile, the fine precipitated second phase can effectively reduce the micro-galvanic corrosion effect between the cathode β phase and the anode α-Mg phase. Therefore, the high corrosion-resistant magnesium alloy of the present application will not exhibit serious accelerated local corrosion behavior. The ordinary commercial magnesium alloy such as AZ91D magnesium alloy will have a serious pitting behavior due to the strong micro-galvanic effect between the coarse second phase and the magnesium matrix, and a very deep pitting pit will be formed, thus exhibiting poor corrosion resistance.

[0071] Figure 2 SEM cross-section image of the corrosion product film layer of the high corrosion-resistant magnesium alloy in Example 1 after immersion in 3.5wt% NaCl solution for 6 days. As can be seen, the thickness of the corrosion product film layer is relatively uniform, and the depth of the corrosion film layer is not more than 50 μm. As can be seen from the element distribution map, the network structure composed of the β-Mg 17 Al 12 The second phase forms a corrosion barrier, which can effectively block the expansion of corrosion to the depth of the matrix. The present application realizes the design and preparation of the high corrosion-resistant magnesium alloy through the formation of the network dense second phase corrosion barrier by microstructure control and the promotion of the densification of the corrosion product film layer on the surface of the magnesium matrix by rare earth Ce micro-alloying. Meanwhile, the present application adds a small amount of low-cost rare earth Ce element, which has the advantages of low cost and large-scale application.

[0072] Figure 3 The cross-section SEM image of the corrosion product of AZ91D magnesium alloy in 3.5wt% NaCl solution after immersion for 6 days in Example 1. It can be seen that the magnesium matrix has a serious pitting behavior, and a deep pitting pit is formed, with a depth of more than 200μm. This is because the coarse β-Mg 17 Al 12 The second phase and the magnesium matrix form a strong micro-electric couple effect, and thus a serious pitting behavior occurs in the magnesium matrix around the β-Mg 17 Al 12 phase. At the same time, since the corrosion product formed by the corrosion of AZ91D magnesium alloy is loose and porous and has no protective effect, the AZ91D magnesium alloy has a continuous accelerated corrosion behavior, and thus a deep corrosion pit is formed.

[0073] In summary, the high-corrosion-resistant magnesium alloy has excellent corrosion resistance, and the corrosion rate is much higher than that of the currently used commercial AZ series magnesium alloy. The manufacturing cost is at the same level as that of the AZ series magnesium alloy, and has a large-scale application potential.

[0074] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present application, but cannot be recognized as the specific implementation of the present application being limited to these descriptions. Those skilled in the art should understand that various changes and deductions can be made in form and details, but they do not deviate from the idea and scope of the present application.

Claims

1. An aluminum-containing high corrosion-resistant magnesium alloy, characterized by comprising, The chemical composition of the high corrosion-resistant magnesium alloy containing aluminum is, in percentage by mass: Al 8.11 wt%, Ce 0.34 wt%, Mn 0.13 wt%, inevitable impurities including Fe 0.0064 wt%, Ni 0.001 wt%, Cu 0.0005 wt%, Si 0.04 wt%, and the balance being Mg; Or, the chemical composition of the high corrosion-resistant magnesium alloy containing aluminum is, in percentage by mass: Al 8.23 wt%, Ce 0.45 wt%, Mn 0.12 wt%, inevitable impurities including Fe 0.0089 wt%, Ni 0.001 wt%, Cu 0.0006 wt%, Si 0.038 wt%, and the balance being Mg; The microstructure of the high corrosion-resistant magnesium alloy containing aluminum is composed of fine point-shaped Mg 17 Al 12 The reticular structure of the second phase composition The preparation method of the high corrosion-resistant magnesium alloy containing aluminum comprises the following steps: S1: according to the proportion of the magnesium alloy, the amounts of pure magnesium, pure aluminum, Mg-Ce intermediate alloy and Mn source are calculated, then the raw materials are prepared, the oxide skins of the raw materials are removed, and the raw materials are preheated, wherein the Mn source includes Mg-Mn intermediate alloy or anhydrous manganese chloride; S2: under the protection of a protective gas, the pure magnesium ingot, the pure aluminum ingot, the Mg-Ce intermediate alloy and the Mn source are melted in a crucible to obtain a magnesium alloy melt; the step S2 comprises: S21: under the protection of SF6 and CO2 mixed gas, the pure magnesium ingot is melted at 680℃, then one of the Mn source, the Mg-Mn intermediate alloy or the anhydrous manganese chloride powder is added at 720-750℃, and the temperature is kept for 10-20 minutes; S22: under the protection of SF6 and CO2 protective gas, the slag on the surface of the melt is removed, the pure aluminum ingot is added at 750℃, and the temperature is kept for 10-20 minutes; S23: under the protection of SF6 and CO2 protective gas, the slag on the surface of the melt is removed, the Mg-Ce intermediate alloy is added at 750℃, and the temperature is kept for 20-30 minutes to obtain the magnesium alloy melt; S3: under the protection of a protective gas, the magnesium alloy melt is stirred, refined, kept and slagged to obtain a refined magnesium alloy melt; the refining temperature is 740-750℃, and the temperature is kept for 3-5 minutes; the keeping temperature is 740-750℃, and the keeping time is 40-50 minutes; S4: under the protection of a protective gas, the refined magnesium alloy melt is cast into a preheated metal mold to obtain a magnesium alloy ingot; wherein the casting temperature is 690-720℃; S5: the magnesium alloy ingot is subjected to solid solution treatment and then aging treatment to obtain the high corrosion-resistant magnesium alloy containing aluminum.

2. A method for producing an aluminum-containing high corrosion-resistant magnesium alloy, characterized by, The preparation method of the high corrosion-resistant magnesium alloy containing aluminum according to claim 1.

3. The production method according to claim 2, wherein In step S5, the solid solution temperature is 390-440℃, and the solid solution time is 5-24 hours.

4. The production method according to claim 2, wherein In step S5, the aging temperature is 180-250℃, and the aging time is 6-48 hours.

Images